United Nations investigators have released a new report that documents grave abuse of children on all sides of the three-year civil war in Syria, estimating almost 10,000 killed in the fighting.

The report details how children have been recruited to fight with the opposition, used as civilian shields, tortured and sexually abused in government detention, and killed and maimed by the thousands. The U.N. estimates that more than 10,000 children have been killed since March 2011, and countless others have been injured from shelling, aerial bombardments and fighting on the ground.

“During the first two years of the conflict, the majority of incidents of killing and maiming of children were attributed to Government forces,” the report says. “However, mainly owing to increased access to heavy weapons and the use of terror tactics, armed opposition groups increasingly engaged in such acts during 2013.”

Among the prominent features of the conflict, the report says, are abduction of children and attacks on schools and hospitals. The report cites government statistics that say more than 3,000 of the country’s 22,000 schools have been damaged or destroyed, and that more than 1,000 schools –20 percent of the schools in the country – have been used as shelters for internally displaced persons. More than 2 million children are not attending school regularly.

The report lists several recommendations to halt the “unspeakable and unacceptable” violations of the human rights of Syrian children, including ending indiscriminate attacks on public spaces and ending “the use of terror tactics, airstrikes, chemical weapons and heavy artillery. The U.N. also calls for fighters to respect hospitals as neutral spaces and allow for humanitarian access to affected populations on all sides of the conflict.